Facsimile transmitter and method of assembling the same

ABSTRACT

A facsimile transmitter includes a lamp for directing a light beam toward a scanner which reflects the light onto a document to be reproduced, picks up the light reflected from the document and directs such light to a photomultiplier operable to send to a reproducing recorder an electrical signal proportional to the intensity of the light and the shade value of the document. The lamp is accurately prelocated and premounted in a permanent holder which is detachably secured to a lamp housing and which, as an incident to attachment to the housing, automatically locates the lamp in a precisely established position to produce light of maximum intensity, the premounted lamp being located in such position by the holder regardless of dimensional irregularities in the lamp. To focus the light beam on the document accurately and to direct the reflected light along an exact path toward the photomultiplier, the scanner is formed as two initially adjustable telescopic units carrying relatively simple plane mirrors adapted to be adjusted into precisely established positions by sliding and rotating the units and thereafter held permanently in such positions by bonding the units rigidly together.

United States Patent [72] Inventors Paul H. Dixon FOREIGN PATENTS Belvidere; 853,849 12/1939 France 240/41(PBM) Paul R. Schmidt, Rockford, Ill. [21] AppLNo. 726,408 Prlmary Exammerlohn M.Horan Filed Ma 3 1968 AssistanrExaminer-Joseph F. Peters,Jr.

y b d L 11 Voit&Osan 45 Patented Jan. 12, 1971 eY n [73] Assignee Dixon Automatic Tool, Inc.

Rockford, 111. a corporation of Illinois ABSTRACT: A facsimile transmitter includes a lamp for 54 FACSIMILE TR NSM N METHOD OF directing a light beam toward a scanner which reflects the ASSEMBLING THE S light onto a document to be reproduced, picks up the hght 6Claims22 Drawing Fig5 reflected from the document and d1rects such light to a photomultipher operable to send to a reproducmg recorder an [52] US. Cl 240/4L35, electrical Signal proportional to the intensity of the light and 29/592'24O/4l240/44'23l3/271339/l76 the shade value of the document. The lamp is accurately 355/51 prelocated and premounted in a permanent holder which is [51] IIlLCl F21V19/02 detachably secured to a lamp housing and which, as an [50] Fleid of Search 240/41, Cidem to attachment to the housing automatically locates the 339/176 7 lamp in a precisely established position to produce light of 31529/592 maximum intensity, the premounted lamp being located in such position by the holder regardless of dimensional irregu [56] References Cited larities in the lamp. To focus the light beam on the document UNITED STATES PATENTS accurately and to direct the reflected light along an exact path 2,004,200 6/1935 Goodlin et a1. 240/41(PBM) toward the photomultiplier, the scanner is formed as two ini- 2,082,954 6/1937 Gustin 240/41(PBM) tially adjustable telescopic units carrying relatively simple 2,132,368 10/1938 Geiger... 240/41 (PBM) plane mirrors adapted to be adjusted into precisely established 2,541,883 2/1951 Morgan .1 240/44.2(X) positions by sliding and rotating the units and thereafter held 3,341,710 9/1967 Cade 240/44.2X permanently in such positions by bonding the units rigidly 3,349,233 10/1967 Angier 240/l.2 together.

l 9 e9 93 91 Z 410 1 11a 9? 3 96 4 10s 10 Ht 1 86 99 94 9 8% e3 I J l I l l I I l l3 us 124 -12a HS\ HS PATENTED JAN 12 I97! sum 1 or 6 f w J My 5 FISL k mm F3 \W 5 WW Q ,T v 3 MWHWIM&MM hm PATENTED mu 2 l9?! SHEET 2 [1F 6 3 3 w 9 4 WM 3 w 3 mu: 6 MY w r m w Ha o m Q I. 5 6 6 Aw V 7 00) W Qfl TTORIQgy PATENTEU JAN 12 I971 SHEET 0F 6 wvazurro Paul 94. DCsLov TO m ELYJ p p 1 p I FACSIMEETRANSMII'I'ER AND METHOD or i ASSEMBLINGTIIESAME BACKGROUND OF THE INVENTION This invention relates to a facsimile transmitter of the type which includes at least one scanner movable across a document to be reproduced and operable to create a signal which varies in proportion to the shading of the document. After suitable conversion, the signal usually is transmitted over telephone wires to a recorder which responds to the signal and produces a facsimile of the scanned document.

More particularly, the invention relates to a facsimile transmitter such as is disclosed in the copending application of Paul H. Dixon, et al., Ser. No. 726,409, filed May 3, 1968 in which the scanner, in moving across the document, receives a light beam directed from an electric lamp, focuses the light in a very small spot on the document as the latter is scanned, picks up the light reflected off of the document, and-directs such movable within the light beam emitted from the lamp.

SUMMARY OFTHE INVENTION The general aim of the present invention is to insure that the intensity of the lightdirected to the light-to-signal transducer will be precisely representative of the shade value of the scanned portion of the document in order to promote the production of sharp and uniform facsimilies.

In keeping with this aim, an object of the invention is to locate the lamp in a precisely established position in the transmitter to effect thedirecting toward the scanner of a light beam of extremely high intensity and thereby reduce the effects of ambient light on the intensity of .the beam directed to the transducer. Another object is to premount and prelocate housing 'in the transmitter and which, as an incident to attachment, automatically locate thelarnp in its precisely established position regardless of dimensional irregularities in thelamp. The invention also resides in the novel construction of the lamp housing and the lamp holders and in the manner of premounting and prelocating the lamps in the holders.

Another object of the invention is to provide in the scanner I a novel reflecting apparatus capable of being mass produced to exacting standards to effect accurate directing of the light .onto the document and toward the transducer. A further object is to form the reflecting apparatus as two separate reflectors which may be located in precisely established positions to focus the light spot accurately on the document and to direct the light reflected fromv the document along an exact path I towardthe light-to-signal transducer. A related object is to provide a new and improved scanner in which the reflectors maybe adjusted relative to one another into their precisely established positions and thereafter fixed rigidly and permanently in such positions. In more detailed aspects, the invention is featured by the construction of the scanner as two basic units to enable relative positioning of the reflectors and by the method of assembling the units to locate the reflectors accurately relative to one another. Also, the invention resides in the novel method of preparing the scanner for installation in the transmitter to insure accurate alignment of the reflectors with the lamp and the transducer.

Other objects and advantages of the invention will become apparent from the following detailed description taken in conjunction with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a front elevation of a new and improved facsimile transmitter embodying the novel features of the present invention.

FIG. 2 is a diagrammatic illustration of the path followed by the light beam as it is directed from the lamp onto the document by the scanner and then is picked up and directed to the transducer.

FIG. 3 is an enlarged fragmentary cross section taken substantially along the line 3-3 of FIG. 1

FIG. 4 is an enlarged fragmentary cross section taken substantially along the line 4-4 of FIG. 3.

FIG. 5 is a fragmentary side elevation of apparatus shown in FIG. 3 with parts broken away and shown in section.

FIG. 6 is an enlarged fragmentary cross section taken substantially along the line 6-6 of FIG. 5.

FIG. 7 is a front elevation of an optical bench and of various apparatus used in locating the lamp and the reflectors in precisely established positions.

FIG. 8 is an enlarged end view of parts shown in FIG. 7.

FIG. 9 is a diagrammatic view of parts shown in FIGS. 7 and 8 and illustrating the adjustment of the reflectors to precisely established positions.

FIGS. 10 to 12 are diagrammatic views showing a simulated light spot and the movements undertaken by the spot as the reflectors are adjusted.

FIG. 13 is a fragmentary cross section taken substantially along the line 13-13 of FIG. 6.

FIG. 14 is an enlarged view of the filament of the lamp.

FIG. 15 is a longitudinal cross section taken through one of the scanner units before assembly of the scanner.

FIG. 16 is a view similar to FIG. 15 but showing the other scanner unit before assembly of the scanner.

FIG. 17 is a perspective view of the scanner after the two units have been assembled.

FIG. 18 is a perspective view of the scanner as completely assembled and in condition for mounting in the transmitter.

FIG. 19 is a fragmentary end elevation of a fixture on the optical bench, which fixture is used to locate the scanner as the latter is prepared for installation in the transmitter.

FIG. 20 is a fragmentary cross section taken substantially along the line 20-20 of FIG. 19.

FIG. 21 is a fragmentary cross section taken along the line 21-21 of FIG. 20.

FIG. 22 is a perspective view of a part shown in FIG. 20.

DESCRIPTION OF THE PREFERRED EMBODIMENT As shown in the drawings for purposes of illustration, the invention is embodied in a facsimile transmitter 25 having a scanning mechanism 26 movable across a document 27 (FIGS. 2 and 3) to be reproduced and operable to detect changes in the shading of any pictures or printed matter contained on the face of the document. As an incident to such detection, an electrical signal is produced which varies in accordance with changes in the shade value of the different areas of the document. The signal usually is transmitted over long distances by one or more telephone lines to a recorder (not shown) which operates to print a facsimile of the scanned document in response to receiving the signal.

A detailed description of the overall construction and operation of the transmitter 25 is contained in the aforementioned copending application and only so much of that description as is necessary to gain an understanding of the features of the present invention will be repeated here. Briefly,

the transmitter includes a frame with a head 29 which supports the scanning mechanism 26 and which is suspended above a base 30 mounted on short legs 31 and formed with a generally flat top surface 33 (FIG. 3) upon which the document 27 is placed. The scanning mechanism moves across the printed upper face of the document from left to right (as viewed in FIGS. 1 and 2) to scan the document line-by-Iine at the same time the document is fed in a horizontal plane beneath the scanning mechanism from the front of the base to the rear of the base (or from right to left as viewed in FIG. 3) by a pair of power-driven feed rollers 34 (FIG. 3) journaled in the base. As the document is fed from one feed roller to the other, it passes across an elongated anvil 35 located between the two rollers and defining a surface which supports and underlies the document during scanning.

Herein, the head 29 is in the form of an inverted boidike enclosure (see FIGS. 1 and 3) overhanging the base 30 and formed with left and right end walls 36 and 37 which journal a pair of pressure rollers 39 (FlG. 3) located near the open lower end of the enclosure in overlying relation with the document 27 to press he latter into frictional engagement with the feed roilers 34. A holddown plate 4i) carried by the head is located between the pressure rollers to hold the document lightly against the anvil 35 and is formed with a longitudinal slot 41 extending along the length of the anvil. The scanning mechanism 26 also is carried within the head and includes a pair of substantially identical optical scanners 43 and 44 alternately operable to make a scanning pass across the document from left to right as viewed in FIGS; l and 2 (to which all directions of movement hereinafter will be referenced unless expressly indicated otherwise).

As shown most clearly in FIGS. 3 and S, the scanners 43 and 44 are mounted on separate carriages 46 and each includes a pair of mounting elements 47 and 49 connected swingably to a horizontal pin 50 rigid with the lower end of the overlying carriage. The two carriages are located on opposite sides of upper and lower power-driven screws 51 and 53 extending between the end walls 36 and 37 and are guided for independent back and forth movement along the screws by guide rods 54 and guide channels 55 extending between the end walls.

During scanning of the document 27, one of the scanners 43, 44 is located initially in a scanning position overlying the slot 41 in the holddown plate 40 (as exemplified by the position of the scanner 43 in FIG. 3) and is driven from left to right in a horizontal path across the upper face of the document through a scanning stroke to detect the shade value of a very narrow line of the document underlying the slot. At the same time, the scanner 44 is located in an inactive position (see FIG. 3) offset laterally from the slot and isdriven reversely or from right to left through a return stroke, the inactive scanner simply returning idiy toward the left end wall 36 to a starting position preparatory to making a scanning pass and not detecting the shade value of the document during such return. The active scanner 43 reaches the end of its scanning stroke at the same time the inactive scanner 44- reaches the end of its return stroke and, at this time, the scanner 43 is swung clockwise (FIG. 3) about its associated mounting pin 50 to an inactive position offset from the slot 4i, and the scanner 44 is swung clockwise about its mounting pin 50 to a scanning position overlying the slot. Thereafter, the scanner 44- is driven from left to right through a scanning stroke to detect the shade value of the succeeding line of the advancing document at the same time the scanner 43 is being driven idly from right to left through a return stroke. As the scanners reach the ends of their strokes, they once again switch positions and reverse directions. As a result, the scanners operate alternately to scan the document continuously with the scanning first being effected by one scanner and then by the other scanner.

The scanners 43 and 44 are driven across the document 27 by the screws Si and 53 which are formed with oppositely spiraled threads 56 and 57 (FIG. respectively, and which are power-rotated in a clockwise direction through gearing 59 driven by a motor and transmission unit 66 on the head 29. Upper and lower drive fingers 61 and 63 (FIG. 3) carried on levers 64 pivoted to the carriages 46 and 65 alternately rock into and out of driving engagement with the threads of the screws to cause the scanners to move across the document in response to rotation of the screws. When one of the lower driving fingers 63 is in driving engagement with the lower screw 53, the associated scanner is driven through its scanning stroke and, when one of the upper fingers ell is in engagement with the upper screw 51, the associated scanner is driven reversely through its return stroke. The lower finger of the scanner 43 is in driving engagement with the lower screw at the same time the upper finger of the scanner 44 is in driving engagement with the upper screw, and vice versa, such that Lil the two scanners are always driven in opposite directions. Cam surfaces (not shown) near the ends of the screws rock the upper finger of each scanner into driving engagement with the upper screw when the scanner approaches the end of its scanning su'oke and rock the lower finger of each scanner into driving engagement with the lower screw when the scanner approaches the end of its return stroke. As the driving fingers are shifted into and out of driving engaigemenhthe levers 64 rock about the pivots as and, through coupling links 66, automatically swing the scanners in proper sequence about the pins 50 between their scanning and inactive positions. Reference is made to the copending applicationinentioned above for a more detailed description of the construction and operation of the mechanism for swinging'the scanners between their scanning and inactive positionsand for driving the scanners alternately through scanning strokes across the document. I l i In order to detect and signal the shade value of the printing on the document 27, a collimated light beam 67 (FIG. 2) emitted from a light source 69 near the left end wall 36 is directed from left to right across the document along the same horizontal path followed by the scanners 43, 44 as the latter move through their scanning strokes, isintercepted by that particular scanner which is being moved throughits scanning stroke and which is disposed in its scanning position overlying the slot 41, and is reflected downwardly through the slot and onto the document by the active scanner as indicated by the rays 70 in FIG. 2. While the light beam 67 is being directed onto the document by the active scanner, the inactive scanner is offset laterally from the beam and does not'affect the light. The light 70 is reflected downwardly by the active scanner, is focused in an extremely small spot 71 (FIG. 2) on the document 27 and is reflected back upwardly toward the scanner as indicated by the rays 73. The intensity of the reflected light 73 varies in accordance with changesin the shade value of the printing or pictures on the document and thus is indicative of the lightness or darkness of that portion of the document upon which the spot 7ll is located at any given time. That is, the intensity of the reflected light 73 increases as lighter areas of the document are scanned by the spot and decreases as the darker areas are scanned. Accordingly, as one of the scanners makes a scanning pass across the document, the intensityof-t-he light 73 changes in proportion to changes in the shading of that particular narrow line of the document scanned by the spot during such pass.

As the light 73 is reflected back upwardly from the document 27, it is picked up by the active scanner and is directed ahead of the scanner and back along the original horizontal path in a collimated beam 74 (FIG. 2) whose intensity, of course, also is representative of the shading of the document. The beam 74 is directed through a lens 75 (shown schematically in FlG. 2) located in the right end wall 37 of the head 29 and is reflected off of a mirror 76 through an iris 77 having an aperture with a diameter of approximately .046 inches to form an integrated light spot while admitting a minimum of ambient light. After passing through the iris, the light is reflected off of mirrors 79 and 8b to a light-to-signal transducer 81 which responds to the light to produce an electrical signal proportional to the intensity of the light. After conversion and amplification, the electrical signal is transmitted to the reproducing recorder which operates in response to reception of the signal to create a facsimile of that portion of the document which was scanned to produce the signal. The transducer til is mounted in a casing 83 (FIG. l) on the outside of the right end wall 37 and herein comprises a photomultiplier tube such as No. 8053 tube sold by The Radio Corporation of America. While a photomultiplier has been illustrated, other types of photosensitive and electrical signaling devices may be used as, for example, a photovoltaic, a photocell, a photoresistive semiconductor, and other similar devices for sensing the intensity of a light beam and producing an electrical signal proportional to such intensity.

the head 29 (see FIG. 6) and takes the form of a small electric lamp having a base 84, a bulb 85 and a coiled filament 86 formed by a number of helically wound turns 87 (FIG. 14) of tungsten or the like. A small 3 volt lamp such as that designated as No. 1874 by the General Electric Company is as largeas is required for use with the present transmitter. The bulb and filament of the lamp 69 are enclosed within a cavity '89 (FIG. 6) formed in a lamp housing 90 which includes a mounting flange 91 attached to the outer side of the left end wall 36 by screws 93. An elongated passage or bore 94 formed through the housing opens into the cavity 89 at one end and is aligned at its other end with a hole 95 (FIGS. 6 and 7) extending through the left end wall 36 such that light from the cavity may pass through the bore and the hole for projection of the beam 67 in a horizontal path'across the'document toward the active scanner 43, 44.

ln passing through the bore 94, the light from the lamp 69 is directed first through a condensing lens 96 (FIG. 6) which is held in a precisely fixed position in the bore by a retainer 97 and an adapter 99. Thereafter, the light passes through an iris 100 having an aperture with a diameter of approximately .004 inches, and is directed through an optical lens 101 which collimates the light rays such that the rays of the beam 67 directed across the document 27 generally parallel one another. With the light beam 67 being collimated, the size or cross-sectional area of the beam striking the active scanner remains substanand in this instance, is approximately .0035 inches in diameter.

To focus-the lens 101 with respect to the iris 100 in order to collimate the light beam 67, the lens is held by a retainer 103 (FIG. 6) in a tubular holder 104 which is selectively shiftable within the bore 94 to enable adjustment of the spacing between the lens and the iris-External threads on the holder are screwed into a threadedinsert 105 fixed in the bore such that the spacing between the lens and the iris may be adjusted simply by rotating the holder and without need of removing the lens from the holder. After the lens has been focused, a lock nut 106 threaded over the holder is tightened against the insert 105 to lock the holder'and the lens in their adjusted positions. The lens usually is'adjusted prior to attaching the lamp housing 90 to the end wall 36 and, after the housing has been attached, is aimed to directthe beam 67 along a horizontal path paralleling the document 27 and spaced upwardly from the document a precise distance of .781 inches. To facilitate aiming of the beam along the correct path and at the .proper height, compressible Teflon. washers 107 (FIG. 6) encircling the screws 93 are sandwiched between the end wall 36 and the mounting flange 91 to allow each screw to be tightened to the degree necessary to attach the housing 90 to the end wall in a position to aim the beam correctly.

To detect the true shade value of the document 27, the light beam 67 and the spot 71 should be of high intensity. in order to reduce the degrading effect of ambient light on the intensity of the beam 74 transmitted to the photomultiplier 81. To increase the intensity of the beam 67 (in terms of lumens, a concave collector mirror 109 (FIGS. 2 and 6) is positioned on the side of the lamp 69 opposite the bore 94 to reflect the light back toward the lamp and into 'the bore. The mirror is disposed in a bore 110 opening into the cavity 89 and aligned with the bore 94, and is held in a precisely fixed position between a pair of retainers 111 and 113.

Light of maximum intensity is produced when the lamp 69 is disposed in a precisely established position (shown in FIG. 6) with the filament 86 centered at the center of curvature of the mirror 109 and located such that the reflected image 871' (FIG. 14) of the helical turns 87 of the filament become interlaced with the actual turns as shown schematically in FIG. 14 to produce a solid spot of light for projection through the iris 100. Thus, by locating the lamp filament in a precisely established position in the lamp housing 90, a light beam 67 of greater intensity is directed toward the scanner to enable better detection of the true shade value of the document 27.

In accordance with one novel aspect of the present invention, the lamp 69 is premounted and prelocated accurately in its own permanent holder 114 (FIG. 6) which is attached releasably to the lamp housing and which, as an incident to being attached to the housing, automatically locates the lamp filament 86 in its precisely established position shown in FIG. 6 without requiring adjustment of the lamp to place the filament in such position. Moreover, all replacement lamps are prelocated accurately in similar permanent holders such that, when one lamp burns out, a new lamp and holder may be attached to the housing 90 with assurance that the filament of the new lamp will be placed in the same precisely established position in the housing even though the lamps vary dimensionally from one another and are not manufactured to strict tolerances.

In the present instance, the lamp holder 114 is located at one side of the lamp housing 90 and comprises four sidewalls 115 (FIG. 6) and an end wall 116 defining a socket 117 of rectangular cross section for holding the base 84 of the lamp 69, the socket having an open end around which extends a mounting flange 118 formed integrally with the sidewalls. The cavity 89 in the housing opens out of one wall 119 of the housing and is aligned with the open end of the socket 117 to receive the bulb 85 and the filament 86 of the lamp when the holder is attached to the housing with the base 84 mounted in the socket.

Before the holder 114 is attached to the housing 90, the lamp 69 is prelocated in an accurate position in the holder so that, when the holder is attached, the filament 86 will be located in the housing in a precise position relative to the mirror 109 and will be disposed exactly as shown in FIG. 6. For this purpose, four nylon or other nonconductive adjusting screws 120 spaced 90 from one another are threaded through the four sidewalls 115 of the holder 114 and an additional adjusting screw 121 is threaded-into the end wall 116 of the holder to hold the base 84 of the lamp spaced from the walls and to enable adjustment of the base in the socket 117 to the position necessary to locate the filament correctly in the housing 90. The lamp is inserted into the socket with the base supported on the screws and with electrical leads 123 (FIG. 6), which are soldered to the terminals of the lamp, extending outwardly of the holder through small holes (not shown) in r the walls. After adjustment of the screws to shift and locate the base precisely in the socket, a quantity of flowable cement 124 (FIG. 6) such as epoxy resin is poured into the socket and is allowed to harden to bond the lamp base rigidly to the walls of the socket and thus hold the lamp permanently in the socket in the position established by adjustment of the screws.

With the lamp 69 held securely in and located accurately relative to the holder 114, the latter is attached to the wall 119 of the lamp housing 90 by four screws 125 (FIG. 5) projecting through the flange 118 on the holder and threaded into the wall 119. Holes in the housing wall 119 receive leader pins 126 (FIGS. 6 and 13) projecting from the adjacent side of the flange to position the holder precisely on the housing and, in addition, the opposing flange and wall surfaces are machined accurately to mate perfectly with one another and thus insure precise positioning of the holder when the screws 125 are tightened. Accordingly, with the base 84 of the lamp previously anchored in an exact position in the socket 117 and with the holder 114 accurately located on the housing 90, the filament 86 is set automatically in its precisely established position in the housing as an incident to attachment of the holder so that light of maximum intensity will be directed through the bore 94 and across the document 27.

In order to locate the lamp 69 accurately in the holder 114 so that the filament 86 will be positioned precisely when the holder is attached to the housing 90, use is made of a master lamp housing 90m (FlGS. 7 and 9) identical to the housing 911 and secured to one end of an optical bench 1.27 with its iris 100m aligned with a telescope 129 (P16. 7) located at the other end of the bench. After the lamp hm been placed in an approximate position in the holder, the latter then is secured to the master housing on the bench, the lamp initially having been positioned in the holder such that the filament $6 faces the iris 100m. With the lamp energized through a voltage source, a technician looks through a viewer 13 0 on the telescope to determine the location of the filament relative to the iris 1mm. Thereafter, the screws 126* and 121 are adjusted inwardly or outwardly to shift the lamp in three mutually perpendicular directions until the technician sees through the telescope that the filament is centered both vertically and horizontally with respect to the iris 100m. Fine adjustments of the screws then are made until a perfectly solid light spot of maximum intensity is seen through the telescope thus indicating that the turns 87 of the filament are interlaced with the turns of the image 87i reflected off of the mirror 109m as shown in FIG. 14. When such a spot develops, the filament is located precisely relative to the mirror to direct light of maximum intensity through the iris 100m of the master housing and, since the actual housing 90 on the transmitter 25 is identical to the master housing, the filament will be located in the same precise position relative to the mirror 109 in the transmitter housing to produce light of the same high intensity when the holder is subsequently attached to the transmitter housing.

After the lamp 69 has been adjusted in the holder 114 to position the filament 86 correctly in the master housing 90m, the holder is detached from the housing and the cement 124 is poured into the socket 117 to hold the lamp permanently in its adjusted position. When the cement has hardened, the heads 131 (FIG. 13) of the screws 120 and 121 are sawed off to leave the outer ends of the screws flush with the walls 115 and 116 of the holder thereby to insure against subsequent turning of the screws to disturb the position of the lamp or to loosen the hardened cement. The lamp 69 with its permanent holder 114 then is ready for attachment to the transmitter lamp housing 90 and, as an incident to such attachment, the filament as is placed in its correct position automatically. When the lamp burns out, the holder is detached and is replaced with a similar holder having a lamp which has been preadjusted and prernounted on the optical bench 127. Accordingly, no adjustments are necessary at the time a new lamp is installed.

lt will be apparent from the foregoing that the use of lamps 69 premounted in individual permanent holders 11 1 which are interchangeable on the lamp housing 91) enables the filament 86 of each lamp to be located correctly in the housing without adjustment at the time of installation even though the filaments or bases of the different lamps vary slightly in size or placement as a result of inaccuracies inherent in high speed manufacture of the lamps. Accordingly, the manufacturers of the transmitter can supply the user with replacement lamps and holders with assurance that, without any elaborate or time consuming adjustments on the part of the user, the lamps will be positioned properly to produce light of maximum intensity and thus promote the production of sharper facsirnilies.

The present invention further contemplates constructing each of the scanners 43, 44 as two telescopic units 133 and 134 (FIGS. 4, 15 and 16) which carry separate and relatively inexpensive reflectors 135 and 136, respectively, for properly focusing the light beam 67 on the document 27 and for picking up the light '73 reflected from the document and accurately directing the light beam 74 to the photomultiplier 81. initially, the two telescopic units are adjustable both angularly and axially with respect to one another to enable relative location of the reflectors in precisely established positions so as to effect proper focusing of the light beam onto the document and proper aiming of the light beam 74 toward the photomultiplier. After being adjusted, the units are fastened together rigidly to hold the reflectors permanently in their precisely established positions.

l-lerein, the unit 133 of the scanner 45 is shown in E16. 15 and comprises a tubular member formed with an axially extending cylindrical bore 137 which opens out of boththe inboard and the outboard ends 139 and 1411 of the unit, the inboard end telescopically receiving the unit'13 l and the outboard end facing the lamp 69 as the scanner travels across the document 27. The light beam 67 directed fromthe lamp passes into the outboard end of the unit and through an achromatic lens 14 1 held in a predetermined "position in the bore by threaded retainers M3. After passing through the lens, the light is directed against the reflector which herein simply c mprises a plane first surface glass mirror located within the bore 137 of the unit and inclined at an angle of about 25 to the horizontal to reflect the light rays 11 downwardly onto the document. The mirror 1351s place d into the bore 137 through an opening 1% at the upper side of unit 133 and is cemented to inclined shoulders formed in the walls of the bore to locate the mirror at the proper angle within the unit.

in being reflected from the mirror 135 onto the document 27, the light rays 70 pass through a hole M6 (FlG. 15) formed in the lower wall of the unit 133 and opening into the bore 137. The hole is covered by a transparent glass window 147 with low reflection optical coatings on both sides and bonded to the outer side of the unit by cement. The window also covers a second hole'149 formed through the lower wall of the unit and opening into the bore. l i

As shown in FIG. 16, the unit 134 for the scanner 43 also comprises a tubular member formed with an axially extending bore 150 which opens out of both the outboard and inboard ends 151 and 152 of the unit. The inboard end 152 of the unit 134 is sized and shaped to telescope with a slidable and rotatable fit into the inboard end of the bore 137 formed through the unit 133 and, when the two units are telescoped together (see H6. 4), the hole 149 in the female unit 133 becomes aligned with a hole 153 (FIG. 16) formed in the lower wall of the male unit 134 and opening into the bore 150.

The light 73 reflected upwardly off of the document 27 passes through the window 147 and the holes 149 and 153 and strikes the reflector 11% carried by the male unit 134. This reflector also comprises a plane first surface glass mirror inclined oppositely of the mirror 135 atan angle of 45 to the horizontal and cemented to a correspondingly inclined surface at the inboard end 152 of the male unit to cover the inboard end of the bore 150. Light reflected off of the pickup mirror 1% is directed into the bore 151) and passes into a combination lens 154 (FIG. 16) fastened in'the outboard end of the bore by retainers 155 and operable to collimate the rays and direct the resulting beam 741 ahead of the scanner toward the iris 7'7 and the photomultiplier 81. Because the rays of the beam 74 are collimated, the cross-sectional area of the beam as received by the photomultiplier is substantially uniform irrespective of the distance of the travelling scanner from the photomultiplier.

For the intensity of the light directed to the photomultiplier $1 to be truly representative of the shade value of the document 27, the light beam 7 1 must be aimed parallel to the document and must be centered with respect to the iris 77 thus requiring that the reflecting face of the pickup mirror 156 be precisely positioned, both angularly and axially, relative to the reflecting face of the mirror 1235. in carrying out the invention, advantage is taken of the two mirrors mounted in the separate units 133 and 1234 to enable such relative positioning of the reflecting faces to be established accurately. For this purpose, the two units, with the mirrors cemented in place, are inserted into a fixture 155 (l lGS. '7 and ti) on the optical bench 127 and are adjusted axially and angularly relative to one another while light is directed against the mirrors to indicate their relative positions. Once the mirrors have been adjusted to correct positions, the two units are fastened together rigidly to hold the mirrors permanently in such positions.

More particularly, the fixture 15S rests on a ground upper surface 1% 13) of the optical bench and is positioned accurately on the bench such that a bore 157 (FIG. 9) extending through the fixture is aligned precisely with'the telescope 129 and with the iris 100m of the master lamp housing 90m on the bench, the master housing being equipped with a lamp 69 for directing a collimated light beam 67: toward the bore. The two units 133 and 134 are placed loosely in the bore 157 with the lens 141 facing the lamp 69 and then are telescoped together into assembled relationship after the telescoping surfaces of the two units have first been coated with flowable epoxy or other suitable cement. Within the bore 157, the units 133, 134 are positioned such that the mirrors 135, 136 face upwardly toward a glass 159 (FIG. 9) forming part of a viewer 160 on the fixture and having a set of cross hairs 161 (FIG.

10) with their center located in vertical alignment with the axis of the bore. The glass 159 is positioned above the axis of the two units the same distance (i.e., .78 inches) that the document 27 is spaced below the centerline of the light beam 67 in the actual transmitter 25. Accordingly, the various elements on the optical bench are set. up in the same manner as the actual elements in the transmitter with the glass 159 simulating the document and with the telescope 129 simulating the iris 77 for directing the light beam 74 to the photomultiplier 81.

With the elements thus set up on the optical bench 127, the light beam 67! is directed into the lens 141 of the female unit 133 and is reflected upwardly by the mirror 135 to form a test spot 71! (FIGS 9 and 10) on the glass 159. Thereafter, the female unit is rotated and shifted axially in the bore 157 until the spot 71 becomes centered on the cross hairs 161 as shown in FIG. 11 and thus locate the mirror 135 in a reference position in which the spot 71: is focused at a distance of .781

inches from the axis of the two units 133, 134 and is located withits center lying in a vertical plane extending through such axis. The female unit then is located in its adjusted position by tightening a clamping screw 163 (FIG. 8) associated with the fixture.

Next, the fixture 155 is turned end-for-end on the optical bench 1'27 and is positioned such that the light beam 67! from the lamp 69 is directed into the lens 154 in the male unit 134. The light 'is' reflected upwardly onto the glass 159 by the mirror 136 and forrnsa light spot on the glass similar to the spot 711. The male unit then is rotated and shifted axially within the female unit 133 until the mirror 136 is axially and angularly positioned to'centerthe light spot on the cross hairs 161 on the glass in the same location that the spot 7lt was centered previously. Thus, when the scanner 43 is installed in the transmitter 25 such thatthe light beam 67 is again directed into the feinale'unit'133 and reflected onto the document 27 by the mirror 135, the resulting tiny spot 71 will be in the exact center of all of the rays of light reflected upwardly off of the document toward the pickup mirror 136 and ultimately will be in the center of the beam 74 and in the center of the light directed throughvthe iris 77 to the photomultiplier 81. As a result, the intensity of the light seen by the photomultiplier will .vary precisely in proportion to changes in the shade value of the scanned portion of the document thereby resulting in the production of more nearly perfect facsimilies.

After the male unit 134 has been rotated and shifted within the female unit 133 to locate the pickup mirror I36 correctly, the male unit is locked in its adjusted position in the fixture 155. The two units then are left undisturbed until the epoxy hardens to bond the units rigidly together and hold the mirrors permanently in their precisely established positions relative to one another.

As an alternative to turning the fixture 155 end-for-end on the optical bench 127 to effect positioning of the pickup mirror 136, the fixture may be left positioned as shown in FIG. 9 in which the light beam 67: is directed into the female unit 133, and thetelescope 129 may be used to determine when the male unit 134 has been shifted and rotated to the correct position to locate the mirror 136 properly relative to the mirror 135. After the female unit 133 has been shifted and rotated within the bore 157 of the fixture as before to center the test spot 71! on the cross hairs 161 as shown in FIG. 10, the technician looks through the telescope 129 to determine the position of the spot relative to a set of cross hairs 164 (FIG. 11) built into the telescope and centered in a position which simulates exactly that of the iris 77 of the transmitter 25. Since the mirror 136 usually will not be positioned correctly when the male unit 134 is first placed into the female unit 133, the light spot 71! and the image of the cross hairs 161 in the beam 74! (FIG. 9) reflected off of the mirror 136 to the telescope thus most often will be off center with respect to the center of the cross hairs 164 as shown in FIG. 11 when the technician first looks into the telescope. The male unit 134 then is rotated and shifted within the female unit to adjust the mirror 136 angularly and axially until the centers of the light spot 71t and the two sets of cross hairs 161, 164 coincide exactly with one another (see FIG. 12) as viewed through the telescope. When these conditions prevail, the test spot 71: is located in the exact center of all of the light picked up by the mirror 131 and thus the actual spot 71 will be centered with respect to the iris 77 when the scanner 43 is attached to the transmitter 25.

Usually, it is desirable to use one of the two above-described methods of locating the mirror 136 as a check on the accuracy obtained by using the other method. In this way, detection and correction can be made of any minor deviations resulting from such factors as distorted refraction of the light as it passes through the lenses 141 and 154 and the window 147.

To advantage, the mirror 135, the lens 141 and the window 147 are sealed tightly to the female unit 133 to establish within the unit an airtight compartment which is charged with an inert gas such as nitrogen to prevent condensation from collecting on and clouding the glass elements. After the two units 133 and 134 have been bonded together, nitrogen is admitted into the unit 133 through a hole 165 (FIG. 15) communicating with the bore 137, such hole being plugged after the compartment has been charged. The nitrogen flows into the bore 150 of the male unit 134 through a passageway 166 (FIGS. 4 and 15) leading between the two units, and thus clouding of the mirror 136 and the lens 154 also is prevented. The mirror 136 and the lens 154 are sealed tightly to the male unit and, in addition, the epoxy establishes an airtight seal around the telescoping surfaces of the two units to prevent the escape of the nitrogen.

In order for the light beam 74 to be aimed correctly at the photomultiplier 81, it is necessary not only that the mirrors and 136 be positioned precisely relative to one another but also that the two scanners 43, 44 be installed in precisely established positions in the transmitter 25 to keep the beam 74 parallel to the document 27 and centered with respect to the iris 77. Also, since the two scanners alternately scan the document, both must be installed identically in order for each to transmit the light beam 74 along the same path.

In another of its aspects, the invention contemplates prelocating each scanner 43, 44 in an accurate position identical to the position which the scanner must occupy to direct the light beam 74 accurately when the scanner actually is installed in the transmitter 25. With the scanner held in its prelocated position, the scanner mounting elements 47 and 49 are fastened to the scanner so that, when the mounting elements are subsequently attached to the pivot pin 50 (FIGS. 3 and 5) in the transmitter, the scanner will automatically assume the same accurate position that was prelocated and will direct the light beam 74 correctly.

Accurate prelocation of each scanner 43, 44 is achieved through the use of a fixture I76 (FIGS. 19 and 20) adapted to be placed on the optical bench 127 and including a coned adjusting chuck 171 (FIG. 26) having a bore 173 aligned with the light beam 67t directed from the lamp 69 in the master lamp housing 96m on the bench. After the two scanner units 133 and 134- have been bonded together, the scanner is placed in the fixture with the outboard end Mill of the female unit 133 seated in the chuck. The outboard end 151 of the male unit 134 is telescoped into a bore 174 extending through a laterally and vertically adjustable slide 175 formed as part of the fixture, the bore being aligned with the telescope ill).

The light beam 67t is directed into the unit and is reflected downwardly by the mirror 135 onto a base H76 of the fixture 170 to form a test spot Tit (FlG. Ill) adjacent a double-lined reticle 177 on the base, the latter being spaced below the center of the light beam 67! at a distance of .781 inches. Thereafter, the scanner is shifted axially by adjusting the chuck Fill and also is rotated within the chuck until the light spot Hz is centered generally on the reticle i77. The techniclan, while looking through the telescope 229, then moves the slide 175 laterally relative to the base 176 with an adjusting mechanism 179 (FlG. 19) to shift the scanner sidewise through a slight distance to center the image of the light spot 71! on the vertical line of the cross hairs lo l of the telescope. Next, the slide is adjusted vertically on the fixture by an adjusting mechanism 180 to raise or lower the scanner and center the image of the light spot 7lt' on the horizontal line of the cross hairs of the telescope thereby to locate the image of the spot appearing in the mirror 136 a distance of .781 inches from the actual spot 71t' on the base. Any necessary final angular, axial, sidewise and vertical adjustments of the scanner then are made until the image of the spot 71t' is centered precisely on both the reticle and the cross hairs shown in FIG. 21. Once the spot is so centered, the position of scanner is such that the spot 71! focuses with a diameter of .0035 inches at a distance of .781 inches below the light beam 67t and lies in the same vertical plane as the longitudinal centerline of the beam.

With the scanner thus positioned, the mounting elements 47 and 49 are attached to the scanner while being held in a reference position (see FIG. 20) which simulates the position assumed by the mounting elements when mounted on the pin 50 in the transmitter 25. As shown in FIG. 18, the mounting elements are in the form of hanger arms having holes 185 in their upper ends for receiving the pin 50 on the scanner carriage 46. At their lower ends, the hanger arms 47 and 49 are formed with generally semicircular cradles 1.86 for receiving the scanner.

To attach the hanger arms 47, 49 to the prelocated scanner in the fixture 170, the arms are slipped over a fixture pin M7 (FIG. 20) simulating to the mounting pin 50 and overhanging the scanner. A semicylindrical shim l8? (FIG. 2%) then is placed on the pin between the two arms to establish the proper spacing between the arms. With the arms hanging on the pin in the same position they subsequently will assume when attached to the pin 50, the scanner is bonded to the cradles 186 of the arms by epoxy which is allowed to set before the scanner is disturbed.

From the foregoing, it will be apparent that, when the hanger arms 47, 49 are attached to the pin 50 in the transmitter 25, the scanner will assume the same accurate position in which it was prelocated in the fixture l'lll. As a result, the light spot 71 will be focused at the proper distance below the light beam 67 and the reflected beam 74 will extend exactly parallel to the document 27 and will be centered with respect to the iris 77. Moreover, each of the scanners all, M will be positioned identically so that the size and direction of the light beam 74 will remain constant regardless of which scanner is actively scanning the document.

We claim:

1. A lamp assembly adapted for use with a facsimile trans mitter and comprising a housing formed with a cavity opening out of one side of the housing, a bore extending through said housing and opening into one side of said cavity, a mirror located in said housing at the other side of said cavity and aligned with said bore, a lamp holder having sidewalls and an end wall defining an open socket, said holder being located icent said one side of said housing with the open end of 'L socket with the open end oi said cavity, an elec' tric lamp having a base located in socket and having a filament located in said cavity between said bore and said mirror to direct light into the bore and to direct light against the mirror for reflection into the bore, a quantity of hardened cement in said socket and rigidly bonding said base to the walls of said socket to anchor the lamp permanently in the socket with the filament located in a precisely established position relative to said mirror, a series of screws threadedin the walls of said holder and extending into said socket into contact with-the base of said lamp, said screws being adjustablerotatably prior to placing of said cement in said cavity in order 'to'shilt the base within the socket to locate the filament in said precisely established position, and said screws being fixed against rotation by the cement when the latter hardens after being placed in said socket he nter end surfaces of said screws being continuous and be flush with the outer sides of the walls of said holder to prevent the screws from being rotated after said cement has hardened, and means releasably attaching said holder to said housing whereby the holder and the lamp may be detached from the housing and replaced with a similar holder and lamp with the filament of such lamp being located automatically in the same precisely established position relative to said mirror as an incident to attachment of the replacement holder to said housing.

2. A lamp assembly as defined in claim 1 in which the surface of said holder adjacent the open end of said socket and the surface of said housing adjacent the open end of said cavity are accurately formed and are disposed in mating face-toface engagement, and further including a series of leader pins in one of said surfaces projecting into a series of holes in the other of said surfaces to locate said holder in a precise position relative to said housing.

3. A lamp assembly for use with a facsimile transmitter and comprising a holder having sidewalls and an end wall defining an open socket, a lamp having a base inserted into said socket and having a filament located outside of said socket,- a series of screws threaded in the walls of said holder and projecting into said socket in engagement with said base to locate the latter in a precisely established position in said socketfa quantity of hardened cement in said socket and rigidly bonding said base to said screws and to the walls of said socket to hold said base permanently in said precisely established position, the outer end surfaces of said screws being continuous and being flush with the outer sides of the walls of said holder to prevent the screws from being rotated after said cement has hardened.

4. A lamp assembly as defined in claim 5 in which said series of screws includes at least four screws threaded into said sidewalls and spaced angularly from one another by approximately 5. A method of assembling and precisely locating an electric lamp in a holder having sidewalls and an end wall defining an open socket for receiving the base of the lamp and having a series of rotatable screws threaded in said walls with their outer ends accessible from the outer side of the socket and with their inner ends projecting into the socket, said method comprising the steps of, inserting the base of the lamp into the socket with the sides and the ends of the base engaging the inner ends of the screws and being held in spaced apart relation with said walls by said screws, threading the screws into and out of said walls to shift the base in at least two directions relative to said sidewalls and to shift the base in a third direction relative to said end wall thereby to locate the base in a precisely established position in said socket, filling said socket with flowable cement and allowing said cement to harden while holding said base in said position with said screws thereby to bond the base rigidly to said walls and anchor the base permanently in said socket, and disabling the outer ends of the screws after said cement has hardened thereby to prevent further turning of the screws.

n. A method as defined in claim 3 in which said screws are disabled by cutting off the outer ends of the screws. 

1. A lamp assembly adapted for use with a facsimile transmitter and comprising a housing formed with a cavity opening out of one side of the housing, a bore extending through said housing and opening into one side of said cavity, a mirror located in said housing at the other side of said cavity and aligned with said bore, a lamp holder having sidewalls and an end wall defining an open socket, said holder being located adjacent said one side of said housing with the open end of said socket aligned with the open end of said cavity, an electric lamp having a base located in said socket and having a filament located in said cavity between said bore and said mirror to direct light into the bore and to direct light against the mirror for reflection into the bore, a quantity of hardened cement in said socket and rigidly bonding said base to the walls of said socket to anchor the lamp permanently in the socket with the filament located in a precisely established position relative to said mirror, a series of screws threaded in the walls of said holder and extending into said socket into contact with the base of said lamp, said screws being adjustable rotatably prior to placing of said cement in said cavity in order to shift the base within the socket to locate the filament in said precisely established position, and said screws being fixed against rotation by the cement when the latter hardens after being placed in said socket, the outer end surfaces of said screws being continuous and being flush with the outer sides of the walls of said holder to prevent the screws from being rotated after said cement has hardened, and means releasably attaching said holder to said housing whereby the holder and the lamp may be detached from the housing and replaced with a similar holder and lamp with the filament of such lamp being located automatically in the same precisely established position relative to said mirror as an incident to attachment of the replacement holder to said housing.
 2. A lamp assembly as defined in claim 1 in which the surface of said holder adjacent the open end of said socket and the surface of said housing adjacent the open end of said cavity are accurately formed and are disposed in mating face-to-face engagement, and further including a series of leader pins in one of said surfaces projecting into a series of holes in the other of said surfaces to locate said holder in a precise position relative to said housing.
 3. A lamp assembly for use with a facsimile transmitter and comprising a holder having sidewalls and an end wall defining an open socket, a lamp having a base inserted into said socket and having a filament located outside of said socket, a series of screws threaded in the walls of said holder and projecting into said socket in engagement with said base to locate the latter in a precisely established position in said socket, a quantity of hardened cement in said socket and rigidly bonding said base to said screws and to the walls of said socket to hold said base permanently in said precisely established position, the outer end surfaces of said screws being continuous and being flush with the outer sides of the walls of said holder to prevent the screws from being rotated after said cement has hardened.
 4. A lamp assembly as defined in claim 3 in which said series of screws includes at least four screws threaded into said sidewaLls and spaced angularly from one another by approximately 90*.
 5. A method of assembling and precisely locating an electric lamp in a holder having sidewalls and an end wall defining an open socket for receiving the base of the lamp and having a series of rotatable screws threaded in said walls with their outer ends accessible from the outer side of the socket and with their inner ends projecting into the socket, said method comprising the steps of, inserting the base of the lamp into the socket with the sides and the ends of the base engaging the inner ends of the screws and being held in spaced apart relation with said walls by said screws, threading the screws into and out of said walls to shift the base in at least two directions relative to said sidewalls and to shift the base in a third direction relative to said end wall thereby to locate the base in a precisely established position in said socket, filling said socket with flowable cement and allowing said cement to harden while holding said base in said position with said screws thereby to bond the base rigidly to said walls and anchor the base permanently in said socket, and disabling the outer ends of the screws after said cement has hardened thereby to prevent further turning of the screws.
 6. A method as defined in claim 5 in which said screws are disabled by cutting off the outer ends of the screws. 